Vertical situation display terrain/waypoint swath, range to target speed, and blended airplane reference

ABSTRACT

A flight information display for the flight deck of an aircraft showing a pictorial side view of the flight path or the area directly in front of the aircraft area having a selected distance of at least 0.5 nautical miles, comprising (a) a pictorial representation to scale of the profile of the highest elevations of a swath of terrain along said path or area, (b) an icon positioned on the left or right side of the display representing the aircraft, the altitude of which is to scale with the height of the terrain, and (c) an altitude reference scale; wherein the width of the swath is at least 0.1 nautical miles and no greater than the distance of the minimum accuracy of the means for determining the aircraft&#39;s location.

BACKGROUND OF THE INVENTION

[0001] In modern flight decks, the primary flight information display(PFD) and the navigation display (ND) are the key displays available forproviding situational awareness to the pilot. Although the primaryflight information display provides aircraft attitude and performanceinformation through the attitude direction indicator (ADI), airspeedtape, heading and track indicator, and vertical speed indicator (VSI),the performance information is not shown in relation to the aircraft'ssurroundings. The navigation display provides fairly complete horizontalsituational awareness with a top down (map) view of the aircraft and itssurroundings. The navigation display tries to address verticalsituational awareness through a vertical path deviation indicator,waypoint altitude constraint information, a range to altitude arc, and aselectable terrain picture from a Terrain Awareness and Warning Systems(TAWS). TAWS provides a contour map of surrounding terrain. Due to thedisplay shading limitations and the nature of a top down view display,the contour map can only provide a general awareness of the surroundingterrain height. Also, to avoid pilot complacency and possible falsealarms on takeoff and landing, some systems may have a “blackout”elevation below which the display provides no terrain information innormal conditions. Even with these vertical situational awarenessfeatures on the navigation display, the information still requires someinterpretation, and approach and landing accidents continue to occur.This leaves the pilot with TAWS to provide both horizontal and verticalsituational awareness of terrain. The pilot may not be able to performan optimal vertical maneuver if the pilot is not aware of the height ofthe surrounding terrain. For flight deck displays that show the terraindirectly in front of the aircraft, the input for this type of device maybe a database of topography information that generates a display basedon position information from the aircraft's navigational equipment.However, the display changes with slight adjustments to the direction ofthe aircraft, making it appear “noisy”. Also, navigational instrumentsfor determining the exact position of an aircraft usually have somedegree of error. For example, if the aircraft's automated navigationalequipment is only accurate to within 10 nautical miles of the exactlocation of the aircraft, and the topography display only shows a “line”of topography directly in front of where the aircraft instrumentsindicate the aircraft is located, the topography display will be not beaccurate as to the topography directly in front of the aircraft if theaircraft's exact position is actually 9.5 nautical miles from thelocation indicated by the navigation equipment. A presentation ofterrain and waypoints along the current track of the aircraft providessome awareness, but during turns the pilot will not see terrain in theprojected path of the turn.

[0002] To assist pilots with final approach and landing, a localizer anda glideslope indicator may be provided on the electronic attitudedirector indicator to give the pilot information as to how much theaircraft is deviating from the ideal landing approach angle, as definedby a radio signal from the runway. When the aircraft is not on thisideal path, the flight deck instruments do not indicate the degree ofcorrection required to return the aircraft to the correct descent path.If the pilot under- or overcorrects the descent angle and cannotposition the aircraft onto a suitable landing approach path in a shortperiod of time, the pilot may have to make a decision to abort thelanding, circle, and begin another landing approach. A system that givesthe pilot better information about the current relationship between theaircraft and the ideal descent and landing approach path will aid thepilot.

[0003] At various times during ascent and descent of an aircraft, it maybe necessary for the aircraft to reach a target speed by the time theaircraft reaches a particular geographic point. The airspeed tape on theprimary flight information display indicates current and selectedairspeeds, but the pilot has to judge how long it will take to achievethe selected airspeed. The pilot then needs to calculate how far theaircraft will travel before the target speed is achieved. Thesecalculations and estimations may not be very precise and may distractthe pilot from performing other duties connected with flying theaircraft and maintaining an accurate mental picture of the situation.

[0004] For many of the flight information displays in the cockpit, thereference mark by which the instrument is read is either fixed with amoving scale to indicate the value of parameter (for example, analtimeter tape) or the reference mark moves with respect to a fixedscale (for example, a vertical speed indicator). If the referenceaircraft symbol on a vertical profile display (VPD) is fixed near thebottom of the display and the aircraft is in a descent, the resolutionof the display for that range of altitudes will be insufficient toprovide the pilot with any increased awareness of the terrain theaircraft is approaching. Similarly if the aircraft symbol is fixed atthe top of the display and the aircraft is climbing, resolution will beinsufficient to increase the pilot's awareness of the airplane'srelationship with the terrain ahead.

[0005] One known type of vertical display provides a terrain picture forthe navigation displays, EHSIs, and standalone weather radar displayunits. Another known vertical profile display depicts the flight plan inan along flight plan presentation. The waypoints are positioned relativeto each other and not on an absolute scale (For example, if waypoint Ais at FL390 and waypoint B has an altitude constraint of FL410, thenwaypoint A will be at a position on the display lower than waypoint B,but otherwise the vertical position of the points will not correlate toany absolute scale). A display that provides better vertical flightsituation awareness to the pilot would be desirable.

SUMMARY OF THE INVENTION

[0006] In one aspect, this invention is a flight information display forthe flight deck of an aircraft showing a pictorial side view of theflight path or the area directly in front of the aircraft area having aselected distance of at least 0.5 nautical miles, comprising (a) apictorial representation to scale of the profile of the highestelevations of a swath of terrain along said path or area, (b) an iconpositioned on the left or right side of the display representing theaircraft, the altitude of which is to scale with the height of theterrain, and (c) an altitude reference scale;

[0007] wherein the width of the swath is at least 0.1 nautical miles andno greater than the distance of the minimum accuracy of the means fordetermining the aircraft's location.

[0008] In another aspect, this invention is a flight information displayfor the flight deck of an aircraft showing a side view of the landingapproach for the aircraft on a runway, comprising (a) a pictorialrepresentation to scale of the profile of the current projected path ofthe descent of the aircraft, (b) a pictorial representation to the samescale of the profile of the vertical glide path of the approach, (c) anicon positioned on the left or right side of the display representingthe aircraft; the altitude of which is depicted to the same scale, and(d) an altitude reference scale.

[0009] In a third aspect, this invention is a flight information displayfor the flight deck of an aircraft comprising (a) a reference point oricon representing the current location of the aircraft, (b) a pictorialrepresentation of at least 0.5 nm of the profile of the projected flightpath of the aircraft, (c) a an icon showing the location at which theaircraft will reach a target speed based on its current speed andacceleration. This display provides an indication of where in thevertical plane and along the flight path the target speed will beachieved.

[0010] In a fourth aspect, this invention is a flight informationdisplay for the flight deck of an aircraft, which comprises (a) an iconhaving a fixed position on the right or left side of the displayrepresenting the aircraft; (b) a vertical altitude scale which changesas the altitude of the aircraft changes so that the altitude numberhorizontally aligned with the aircraft icon is the current altitude ofthe aircraft and the aircraft icon is located vertically along thealtitude reference scale while always being in view, and (c) a pictorialrepresentation of a lateral view of any terrain directly in front of theaircraft.

[0011] The above-described display of the invention provides flightinformation to assist the pilot in avoiding terrain collisions or makingmore efficient and safe landing approaches. The displays provide thisinformation in a format that is relatively intuitive for the pilot tounderstand without substantial analysis, interpretation, false alarms,or unnecessary distraction from other duties, and

[0012] conforms to standard graphical depictions used on approach chartsand other places in the flight deck, thereby allowing the pilot to makeany necessary adjustments to the speed and direction of the aircraftrelatively quickly and precisely.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The preferred and alternative embodiments of the presentinvention are described in detail below with reference to the followingdrawings.

[0014]FIG. 1 illustrates one embodiment of a Vertical Profile Displayproviding a view of the vertical terrain along the track of theaircraft.

[0015]FIG. 2 is a schematic of one embodiment of a terrain swath used togenerate the vertical profile display.

[0016]FIG. 3 illustrates a display that shows the terrain in the path ofthe turn, taking into account the aircraft's cross track acceleration,in which case the boundary of the swath also rotates away from the trackline with the origin of the aircraft as the rotation point.

[0017]FIG. 4 illustrates a vertical situation display having atriangular-shaped icon positioned towards the left side of the display,which represents the aircraft.

[0018]FIGS. 5, 6, and 7 illustrate one embodiment of a display thatgives the pilot information about the location at which the aircraftwill reach a target speed.

[0019]FIG. 8 shows a display with a collection of points where thetarget speed will be achieved at various angles.

[0020]FIG. 9 illustrates an embodiment of a display wherein therange-to-target speed symbol is located on the flight vector on anavigation display.

[0021]FIG. 10 illustrates an embodiment of a display wherein therange-to-target speed symbol is located on the flight vector on athree-dimensional perspective map.

[0022]FIG. 11 illustrates an embodiment of a display wherein therange-to-target speed symbol is located on head up display.

DETAILED DESCRIPTION OF THE INVENTION

[0023] The flight information display of the first aspect of theinvention specifies a region in front of the aircraft to show terrain,waypoints and runways, on a vertical profile display. The source of theinformation to generate the profile of the terrain display may comefrom, but is not limited to, an on-board computer having a database oftopographical information or a ground mapping radar. A Vertical ProfileDisplay (VPD), provides a view of the vertical plane along the track ofthe aircraft (see FIG. 1), and may also display other information suchas data on aircraft performance or target altitude information.

[0024] The terrain depicted on the display is the highest terrain thatis within a specified swath of terrain along the direction of theairplane's track. Specifically, the terrain value depicted at any givendistance from the airplane symbol is the maximum terrain height along anarc at that given distance centered on the airplane and bounded by theedges of the swath. The swath may be of any suitable width or shape, butpreferably widens as the distance from the airplane increases to takeinto account any slight variations from a straight-line trajectory inthe path of the airplane. Most preferably, the swath is approximatelythe shape of a triangle with a corner at the nose of the airplane. Inone embodiment, the projected swath also includes terrain in thedirection of a turn because the swath preferably widens in the directionof any turns. In this embodiment, an algorithm calculates the swath tobe projected and bases the width of the most distant part on the swathby the sensed crosstrack acceleration.

[0025] The width of the terrain used for input to generate the displayis preferably at least about 0.15 nautical miles (nm), more preferablyat least 0.30 nm. The width is also preferably at least the resolutionof the terrain database, most preferably at least the requirednavigation performance (RNP) for the current phase of flight or landingapproach; but preferably no greater than 3 times the RNP for that phaseof flight or approach, and more preferably no greater than 2 times theRNP for that phase of flight or approach. The distance in front of theaircraft depicted in the display is preferably at least 0.5 nm. If theflight deck also contains on a separate top-down display of terrain infront of the airplane to the compass rose the distance depicted on theside-view display preferably at least half the range that is shown onthe top-down display of terrain in front of the airplane to the compassrose; but is preferably no greater than 2 times the range. Mostpreferably, the display's range is the same as the range that is shownon the map in front of the airplane to the compass rose.

[0026] If the aircraft is on a straight path, the terrain swath used togenerate the display is preferably in the shape of a rectangle with atapered end at the nose of the aircraft. In one embodiment, from thenose of the aircraft to 2.5 nm in front of the aircraft, the width ofthe terrain swath is 0.25 nm about the track of the aircraft (see FIG.2). From 2.5 nm to 5 nm, width of the terrain swath is preferably 0.75nm about the track of the aircraft. From 5 nm to the edge of thedisplayed VSD range, the width of the swath is preferably in the rangeof from 1 to 8 nm, as illustrated in Table 1. TABLE 1 Width of 5 nm toend of display section vs. range selection. EFIS Preferred Swath RANGEWidth 10 nm 1 nm 20 nm 2 nm 40 nm 4 nm 80 nm 8 nm 160 nm  8 nm 320 nm  8nm 640 nm  8 nm

[0027] The varying swath takes into account coarse display resolution ofrange map scale settings greater than 10 nm (see Table 1). For distancesclose to the aircraft (5 nm and less) the swath of the terrain shown ispreferably relatively narrow. Further away from the aircraft, thedisplay shows the highest terrain in a larger swath.

[0028] In a preferred embodiment, if the aircraft is turning, thedisplay shows the terrain in the path of the turn, taking into accountthe aircraft's cross track acceleration, in which case the boundary ofthe, swath also rotates away from the track line with the origin of theaircraft as the rotation point (see FIG. 3). The left side of the swathwill rotate left if the aircraft is turning left while the right sidewill stay straight along the current track. Then the right side of theswath will rotate right if the aircraft is turning right and the leftside of the swath will stay straight along the current track. This givesa wedge of the terrain in front of the aircraft. The side of the swathpreferably rotates φ/2 degrees where φ is the bank angle of anon-accelerated constant altitude turn that produces the current crosstrack acceleration.

[0029] The use of a relatively narrow swath of terrain to generate thedisplay provides a terrain picture that has a more steady, filteredappearance than a display which only uses data from the line of terraindirectly in from of the aircraft, while still showing relevant terrainin front of the aircraft. Preferably, waypoints in this swath are alsoshown.

[0030] In the display of the second aspect of the invention, a verticalsituation display includes a depiction of the glide slope of an approachfor a runway when the aircraft is in a landing approach for theparticular runway. The display also depicts the current angle of descentof the aircraft as a projected flight path on the display. If theaircraft is not within the glideslope for the runway, this type ofdisplay allows the pilot to directly see the extent to which the descentangle needs to be corrected. FIG. 4 illustrates a vertical situationdisplay. On the bottom portion of the display, a triangular-shaped icon41 is positioned towards the left side of the display, which representsthe aircraft. However, any shape of icon or reference symbol may beused. The flight direction of the aircraft is depicted from left toright of the aircraft icon, and a vertical elevation scale 42 on theleft the side of the display provides information on the altitude ofvarious points along the projected descent path. The glide slope isdepicted as an overlay on the flight path of the aircraft using anysuitable combination of lines or symbols. Preferably, the glide slope 43is depicted in the same way as it is depicted in the same manner as itis shown in a standard approach chart with which the pilot is familiar.Typically, the glide slope is depicted as having the shape of narrowtriangle. Such approach and landing approach charts are specific to eachrunway and are available from several companies and organizations, suchas Jeppesen and National Oceanic and Atmospheric Service.

[0031] In the flight information display of the third aspect of theinvention, a range-to-target speed symbol on the display automaticallyprovides flight information in an operationally intuitive manner. Thissymbol can be shown on any type of flight deck display that shows thehorizontal path of aircraft in any form, and may be any type of symbolthat indicates the position or time where the selected speed will beachieved. The flight path vector can be colored to indicate thisinformation on the primary flight information display, navigationdisplay, or vertical situation awareness displays. There is no limit tohow this information is depicted on the various displays. Therange-to-target speed information is shown symbolically instead oftextually to provide the pilot a clear and intuitive picture of theaircraft's situation. Examples of types of displays which mayincorporate this type of symbol include vertical profile displays,primary flight information displays, navigation displays, head updisplays, perspective displays/virtual reality displays, andthree-dimensional displays. A symbol on the display of the verticalflight path of the aircraft indicates the position along the verticalflight path vector where the current airspeed is predicted to equal theselected airspeed, given the current performance of the aircraft. Anysymbol or icon may be utilized, but in one preferred embodiment, theflight path of the aircraft is shown as a white or light-colored vectoremanating from the nose of the aircraft symbol, and the position atwhich the aircraft will reach the target speed is shown as adarker-colored dot (for example, a green dot) at a position along thevector. As a pilot initiates an approach to the airport, he must achievethe correct flight path and be at appropriate airspeeds before reachinga “final” position at which the pilot must decide whether to land orabort the landing and circle around to make another approach. Therange-to-speed dot allows the pilot to assess the status of the descentand to recognize earlier situations that if uncorrected may lead toaircraft damage. A high speed landing while on path can result in atailstrike, runway over runs, or hard landings resulting in airframedamage and possible injury to passengers. Avoiding these situations willsave the airline from lost revenue and repair expenses that would resultfrom approach and landing incidents.

[0032] Although there can be many different ways of showing thisposition and related data, one preferred way of showing this position isby a filled/unfilled circle along the flight path. If the differencebetween the actual speed and target speed is less than a specifiedmaximum, such as 5 knots, then the dot will be at the nose of theaircraft symbol as shown in FIG. 5. This is one type of hysteresis thatcan be used so that the dot will act smoothly to changes in aircraftperformance when nearing the target speed. If the speed difference isgreater than the specified maximum but is converging to that number, theposition where the target speed will be achieved is represented on thedisplay as a filled green circle, if the aircraft is projected to reachthat speed at a distance no greater than the range of the display, asshown in FIG. 6. If the speed difference is not converging to thespecified maximum or the location where the target speed will beachieved is outside the range of the display, then the filled greencircle becomes a larger unfilled circle and is positioned at the edge ofthe display along the predicted flight path as shown in FIG. 7. Bykeeping the symbol on the display, the pilot will always be aware of theaircraft's speed situation and trend. FIG. 8 shows a display havingseveral dots, each of which indicate the location at which the aircraft1 will achieve the target speed at various flight angles. For example,at flight path 3 having flight angle 2, the target speed will beachieved at point 4. At flight path 5, the target speed will be achievedat point 6. If desired, a line 7 may connect the dots, a targetspeed/distance may be selected, and the flight angle/accelerationnecessary to achieve the target speed/distance may be determined.

[0033] The dot's position on the display is calculated (Equation 1),using groundspeed, inertial acceleration, and the time it takes toachieve the selected airspeed. Groundspeed and inertial acceleration areused to calculate the position because the display is referenced to theground and the aircraft. The dot's vertical position is calculated inEquation 2 using vertical speed, current airspeed acceleration, and timeto achieve the selected airspeed. Sensors measure groundspeed andinertial acceleration, but not time or airspeed acceleration. Therefore,the invention calculates the time to achieve the selected speed inEquation 3 using selected airspeed, current airspeed, and currentairspeed acceleration. Selected airspeed is an input from the pilot orflight management computer and current airspeed is a measured value.Current airspeed acceleration is calculated in Equation 4 by dividingthe change in airspeed by the change in time. The calculated positioninformation is then scaled to the display settings to depict the correctposition on the display.

d _(achieve) =vg _(current)*(t _(achieve)/3600)+(½*ag*cos(γ)*t_(achieve) ²)/6067   Eq. [1]

h _(achieve) =vs _(current)*(t _(achieve)/60)+½*a _(current)*sin(γ)*t_(achieve) ²   Eq. [2]

t _(achieve)=((v _(selected) −v _(current))*6067)/(3600*a _(current))  Eq. [3]

a _(current)=((v _(final) −v _(initial))*6067)/(3600*(t _(final) −t_(initial)))   Eq. [4]

[0034] where: a=airspeed acceleration in ft/sec²; v=calibrated airspeedin knots; t=time in seconds; d=distance along the ground in rm; h=heightin feet; vg=Ground Speed in knots; vs=Vertical Speed in ft/min;ag=Inertial acceleration along γ in units of g (32 ft/sec²); γ=FlightPath Vector in degrees. Airspeed acceleration does not have to be anunfiltered instantaneous current airspeed acceleration as defined byEquation 4; averaging the data over a short period of time will producea more steady moving symbol.

[0035] This invention can be further utilized to provide a collection ofpoints where the target speed will be achieved at various flight angles.As shown in FIG. 13, at flight angle 1 the selected speed will beachieved at A and at flight angle 2 the selected speed will be achievedat B, etc. All these points at various flight angles will produce astraight line in on the display. To generate this line or a set of dots,the acceleration needs to be predicted at the various flight angles.This line would enable one to see how to make trade-offs betweenairspeed and altitude.

[0036] The range-to-target speed symbol can be located on the flightvector on a vertical situation awareness display (FIG. 1), navigationdisplay (dot 91 on FIG. 9), three-dimensional perspective map (dot 101on FIG. 10), head up displays (dot 111 on FIG. 11), or any type ofvirtual reality flight information display. The information can bedisplayed so that the symbology provides an estimate of where the pilotwill achieve the target speed along the flight plan instead of theflight path.

[0037] The fourth aspect of the invention is a blended moving/fixedaircraft reference symbol. The aircraft symbol (white aircraft inFIG. 1) begins at the bottom of the display (on top of the horizontalgray shade) when the aircraft is on the ground. The bottom altitude ofthe display is defined to be the take off field elevation during thetake off portion and the landing field elevation during the landingportion of flight. When the aircraft takes off, the aircraft will movevertically up along he altitude scale until it reaches a fixed point thetop half of the display, preferably about two-thirds of the distancefrom the bottom of the display. At that point the aircraft is positionedat fixed on the display and the scale and background data move down awayfrom the aircraft symbol as the aircraft climbs. The opposite is truefor the descent case. The aircraft symbol stays fixed point on thedisplay until the landing field elevation altitude reaches the bottom ofthe display. When the landing field elevation altitude becomes even withthe bottom of the display, then the aircraft symbol moves down towardthe landing field elevation altitude. The algorithms are straightforwardas is the logic that switches between the vertically moving and thevertically fixed aircraft symbol. The aircraft is always fixedhorizontally, adjacent to the left or right side of the display. Themotion of the aircraft display allows the display to be relatively smalland yet retain a high level of utility. This saves valuable displayspace, room in the cockpit that would be taken up by another displayscreen, and allows other pieces of information to remain visible to thepilot.

[0038] All of the visual displays of the invention may be electronicallygenerated by any suitable means for converting electronic flight andterrain information, and any other data as appropriate, into a cockpitvisual display having the above-described criteria and features. Exampleof electronic flight information systems that generate alarms and/ordisplay other types of flight information, or have other formats, aredescribed in U.S. Pat. Nos. 5,936,552, 5,839,080; 5,884,222; and5,638,282.

What is claimed is:
 1. A flight information display for a flight deck ofan aircraft, the display comprising: a first icon representing a currentlocation of the aircraft; a pictorial representation of at least 0.5 nmof a profile of a projected flight path of the aircraft; and a secondicon showing a location at which the aircraft will reach a target speedbased on its current speed and acceleration, the display providing anindication of where in a vertical plane and along the flight path thetarget speed will be achieved.
 2. The display of claim 1, wherein thesecond icon is located toward the nose of the aircraft when a differencebetween current speed of the aircraft and the target speed is less thana predetermined threshold.
 3. The display of claim 2, wherein the secondicon is located toward the location at which the aircraft will reach thetarget speed and the icon has a first size when the difference betweencurrent speed of the aircraft and the target speed is greater than thepredetermined threshold and the aircraft is projected to reach thetarget speed at a distance within range of the display.
 4. The displayof claim 3, wherein the second icon is located toward an edge of thedisplay away from the first icon and the second icon has a second sizethat is larger than the first size when the difference between thecurrent speed of the aircraft and the target speed is greater than thepredetermined threshold and the aircraft is projected to reach thetarget speed at a distance beyond the range of the display.
 5. Thedisplay of claim 1, further comprising a plurality of second icons, eachof the plurality of second icons indicating a location at which theaircraft will achieve the target speed at a different flight angle. 6.The display of claim 1, wherein location of the second icon iscalculated according to the equations: d _(achieve) =vg _(current)*(t_(achieve)/3600)+(½*ag* cos(γ)*t _(achieve) ²)/6067   Eq. [1]h_(achieve) =vs _(current)*(t _(achieve)/60)+½a _(current)*sin(γ)t_(achieve) ²   Eq. [2]t _(achieve)=((v _(selected) −v_(current))*6067)/(3600*a _(current))   Eq. [3]a _(current)=((v _(final)−v _(initial))*6067)/(3600*(t _(final) 31 t _(initial)))   Eq. [4 ]where: a=airspeed acceleration in ft/sec²; v=calibrated airspeed inknots; t=time in seconds; d=distance along the ground in nm; h=height infeet; vg=Ground Speed in knots; vs=Vertical Speed in ft/min; ag=Inertialacceleration along γ in units of g (32 ft/sec²); γ=Flight Path Vector indegrees.